[special-K]

They should have checked that bushing for wear. First of all,I can only speculate,but any good shop would look for the cause of the bad seal...excess wear. It's one thing if a seal is bad from being dry or age. But,if it is rounded out it's obviously from a worn bushing. I believe that would have been obvious if the seal leaked by the time you got home. I don't call myself a mechanic but after servicing my own vehicles all my life I have enough sense to check for wear when servicing a moving part. I also feel I'd be a fool to only fix the effect and not the cause. The primary cause here was low and/or contaminated lubricant that caused the bushing to wear that caused the seal to go. To any mechanic that should be obvious. I would inspect the carrier bearings as well as the ring & pinion. For that much money I'd think you would have gotten a "complete" rear job,not a quicky.